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Faithful genome partition during cell division relies on proper congression of chromosomes to the spindle equator before sister chromatid segregation. Here we uncover a kinesin-7 motor, kinetochore-associated kinesin 1 (KAK1), that is required for mitotic chromosome congression in Arabidopsis. KAK1 associates dynamically with kinetochores throughout mitosis. Loss of KAK1 results in severe defects in chromosome congression at metaphase, yet segregation errors at anaphase are rarely observed. KAK1 specifically interacts with the spindle assembly checkpoint protein BUB3.3 and both proteins show interdependent kinetochore localization. Chromosome misalignment in BUB3.3-depleted plants can be rescued by artificial tethering of KAK1 to kinetochores but not vice versa, demonstrating that KAK1 acts downstream of BUB3.3 to orchestrate microtubule-based chromosome transport at kinetochores. Moreover, we show that KAK1's motor activity is essential for driving chromosome congression to the metaphase plate. Thus, our findings reveal that plants have repurposed BUB3.3 to interface with a specialized kinesin adapted to integrate proper chromosome congression and checkpoint control through a distinct kinetochore design.

The α-Aurora kinase is a crucial regulator of spindle microtubule organization during mitosis in plants. Here, we report a post-mitotic role for α-Aurora in reorganizing the phragmoplast microtubule array. In Arabidopsis thaliana, α-Aurora relocated from spindle poles to the phragmoplast midzone, where it interacted with the microtubule cross-linker MAP65-3. In a hypomorphic α-Aurora mutant, MAP65-3 was detected on spindle microtubules, followed by a diffuse association pattern across the phragmoplast midzone. Simultaneously, phragmoplast microtubules remained belatedly in a solid disk array before transitioning to a ring shape. Microtubules at the leading edge of the matured phragmoplast were often disengaged, accompanied by conspicuous retentions of MAP65-3 at the phragmoplast interior edge. Specifically, α-Aurora phosphorylated two residues towards the C-terminus of MAP65-3. Mutation of these residues to alanines resulted in an increased association of MAP65-3 with microtubules within the phragmoplast. Consequently, the expansion of the phragmoplast was notably slower compared to wild-type cells or cells expressing a phospho-mimetic variant of MAP65-3. Moreover, mimicking phosphorylation reinstated disrupted MAP65-3 behaviors in plants with compromised α-Aurora function. Overall, our findings reveal a mechanism in which α-Aurora facilitates cytokinesis progression through phosphorylation-dependent restriction of MAP65-3 associating with microtubules at the phragmoplast midzone.

The spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during cell division by monitoring kinetochore-microtubule attachment. Plants produce both sequence-conserved and diverged SAC components, and it has been largely unknown how SAC activation leads to the assembly of these proteins at unattached kinetochores to prevent cells from entering anaphase. In Arabidopsis thaliana, the noncanonical BUB3.3 protein was detected at kinetochores throughout mitosis, unlike MAD1 and the plant-specific BUB1/MAD3 family protein BMF3 that associated with unattached chromosomes only. When BUB3.3 was lost by a genetic mutation, mitotic cells often entered anaphase with misaligned chromosomes and presented lagging chromosomes after they were challenged by low doses of the microtubule depolymerizing agent oryzalin, resulting in the formation of micronuclei. Surprisingly, BUB3.3 was not required for the kinetochore localization of other SAC proteins or vice versa. Instead, BUB3.3 specifically bound to BMF3 through two internal repeat motifs that were not required for BMF3 kinetochore localization. This interaction enabled BMF3 to recruit CDC20, a downstream SAC target, to unattached kinetochores. Taken together, our findings demonstrate that plant SAC utilizes unconventional protein interactions for arresting mitosis, with BUB3.3 directing BMF3's role in CDC20 recruitment, rather than the recruitment of BUB1/MAD3 proteins observed in fungi and animals. This distinct mechanism highlights how plants adapted divergent versions of conserved cell cycle machinery to achieve specialized SAC control.

The kinetochore scaffold 1 (KNL1) protein recruits spindle assembly checkpoint (SAC) proteins to ensure accurate chromosome segregation during mitosis. Despite such a conserved function among eukaryotic organisms, its molecular architectures have rapidly evolved so that the functional mode of plant KNL1 is largely unknown. To understand how SAC signaling is regulated at kinetochores, we characterized the function of the KNL1 gene in Arabidopsis thaliana. The KNL1 protein was detected at kinetochores throughout the mitotic cell cycle, and null knl1 mutants were viable and fertile but exhibited severe vegetative and reproductive defects. The mutant cells showed serious impairments of chromosome congression and segregation, that resulted in the formation of micronuclei. In the absence of KNL1, core SAC proteins were no longer detected at the kinetochores, and the SAC was not activated by unattached or misaligned chromosomes. Arabidopsis KNL1 interacted with SAC essential proteins BUB3.3 and BMF3 through specific regions that were not found in known KNL1 proteins of other species, and recruited them independently to kinetochores. Furthermore, we demonstrated that upon ectopic expression, the KNL1 homolog from the dicot tomato was able to functionally substitute KNL1 in A. thaliana, while others from the monocot rice or moss associated with kinetochores but were not functional, as reflected by sequence variations of the kinetochore proteins in different plant lineages. Our results brought insights into understanding the rapid evolution and lineage-specific connection between KNL1 and the SAC signaling molecules.

The study on forecasting demand for online car-hailing holds substantial implications for both online car-hailing platforms and government agencies responsible for traffic management. This research proposes an enhanced Empirical Mode Decomposition Long-short Term Memory Neural Network (EMD-LSTM) model. EMD technique reduces noise and extracts stable intrinsic mode functions (IMF) from the original time series. Genetic algorithm is deployed to improve the K-Means clustering for determining optimal clusters. These sub time series serve as input for the prediction model, with combined results giving final predictions. Experimental data from Didi includes Haikou's car-hailing orders from May to October 2017 and Beijing's from January to May 2020. Results show improved EMD-LSTM reduces instability and captures characteristics better. Compared to unmodified EMD-LSTM, RMSE decreases by 3.50%, 6.81%, and 6.81% for the three datasets, and by 30.97%, 20%, and 9.24% respectively compared to single LSTM model. [ABSTRACT FROM AUTHOR]

The preparation of spherical TATB is a key and challenging research focus in the field of energetic materials. In this paper, microspherical TATB was successfully prepared by the oil-in-oil emulsion method with DMSO and BMIM as solvents for the first time. The optimal process conditions for oil-in-oil emulsions were obtained, and the morphology, structure, particle size distribution, specific surface area, and thermal decomposition performance of the spherical TATB were characterized. The results showed that the optimal process conditions for emulsion stability were as follows: the ratio of continuous to discontinuous phases was 5/5, Tween-80 was used as the surfactant, and the dosage of the TATB raw material was 1%, which could form a stable emulsion. The crystal structure of the TATB samples prepared from the stable emulsion did not change, but only the morphology was changed. The prepared TATB was microspherical with a particle size distribution D50 of 17.5 μm, and the specific surface area was 1.639 m2 g−1. Compared with TATB, spherical TATB exhibited a unique nanostructure on its surface, which caused its thermal decomposition exothermic peak to advance by 8.5 °C and activation energy to decrease by 82.71 kJ mol−1. This method is expected to provide new insights into the spherization of other insoluble explosives. [ABSTRACT FROM AUTHOR]

Timely and powerful diagnostic means can achieve better therapeutic effects, reduce disease torment, and improve survival rate. As a powerful non‐invasive spectroscopy technology, surface‐enhanced Raman scattering (SERS) have testified to be a great potential candidate for extensive early clinical disease diagnosis. In recent years, the introduction of SERS label, combined with other analysis modes or artificial intelligence, and the emergence of miniaturized devices have made SERS technology more advantageous in early diagnosis of diseases. This review focuses on the research progress of SERS dominated analytical strategies in the field of early disease diagnosis in the past five years. The main content includes the application of label‐free SERS detection; the construction of label SERS methodologies for various disease markers; SERS dominated multimode early disease diagnosis strategies; integration of SERS and artificial intelligence; portable Raman equipment and SERS imaging; and opportunities and trends for SERS diagnostic technology in the future. [ABSTRACT FROM AUTHOR]